For current Third Generation Partnership Project (3GPP) Long Term Evolution (LTE) systems, uplink access is based on random access at the initial stage. Evolved NodeBs (eNBs) usually do not consider channel quality when allocating channels at the initial stage. In LTE there are random access channels for a user equipment (UE) to access, and UEs compete for access using different codes. There is a collision probability, and if collision happens the UEs back-off. If there is no collision, the eNBs assign resources for uplink data transmission and inform the assignments to the UEs using control channels.
Although current standards support channel quality reporting for the uplink, the channel quality reporting usually happens during data transmission and can result in a large amount of overhead, both in time and complexity for eNBs. This is typically not suitable for the case of a large number of UEs.
In the next generation cellular network, machine-to-machine (M2M)-type of communications will have wide application. M2M communications systems are usually characterized by large numbers of users, each with low data volumes and high delay-tolerance. Current systems should be adapted to accommodate to this trend. For example, if there are a large number of users, such as in M2M transmissions, and there is no mechanism to limit users, severe performance degradation may occur due to collisions, resulting in many resources being wasted.